When Work Brings the Heat: Your Guide to Heat Stress Risks and Solutions

You can't change the weather, but you can change your approach to working in the heat.

• By Alsie Nelson
• Mar 01, 2019

Weather patterns are changing. The planet's getting warmer. And, in fact, all but three of the hottest years on record have occurred since 2000. On average, excessive heat causes 650 deaths in the United States every year; 39 of those took place on the job in 2016—double the number that occurred only two years prior.

Construction workers in particular take the brunt of the burn, which makes sense when you think about their exposure to unpredictable outdoor temperatures. Services-providing industries, such as trade, transportation, warehousing, and utilities, account for a large percentage of the remaining occupational fatalities.

Know the Risk
Heat stress occurs when the body's means of controlling its internal temperature starts to fail. Once the body’s temperature reaches 99.7° F (37.6° C), heat stress has begun to affect the body. At 104° F (40° C), it becomes susceptible to severe damage. As little as 30 minutes of 104° temps can cause cellular damage to the brain or even death.

Two factors contribute to how heat stress affects the body: personal and environmental. Some workers are at greater risk before they ever step foot in the heat due to personal factors: being older or overweight, having heart disease or high blood pressure, or taking medications that act as diuretics or do not react well to extreme heat.

The second contributing factor is environmental and accounts for anything that impacts the body externally: High temperatures; direct sunlight; humidity; limited air movement; hot equipment; reflected heat from the ground, water, or objects; and clothing/PPE choices are chief among them.

Heat-Related Illnesses
Heat rash, heat cramps, heat exhaustion and heat stroke are the four most common Heat-Related Illnesses (HRIs).

Heat Rash

How it happens: occurs when sweat ducts become clogged and sweat can’t get to the surface of the skin

Symptoms: red blister-like eruptions, bumps, and an itching sensation

How to treat it: keep the skin dry and rest in a cool place

Heat Cramps

How it happens: salt and moisture levels are depleted through excessive perspiration

Symptoms: painful spasms, usually in the legs or abdomen

How to treat it: move to a cool, shaded area, apply something cool, drink plenty of fluids (consider an electrolyte solution)

Heat Exhaustion

How it happens: prolonged exposure to high temperatures and inadequate hydration, causing body tempartures to rise

Symptoms: headaches, weakness, mood change, feeling sick, pale and/or clammy skin

How to treat it: move to a cool, shaded area, apply something cool, drink plenty of fluids and monitor

Heat Stroke

How it happens: when the body becomes unable to control its core body temperature

Symptoms: pale skin, nausea, vomiting, confusion

How to treat it: seek medical attention immediately

Prevention and Solutions
You can't change the weather. But you can change your approach to working in the heat.

Evaporative Cooling
Evaporative cooling is a simple, effective, and relatively inexpensive approach that can be used in outdoor and indoor environments but works best in drier, low-to-moderately humid conditions with sufficient airflow. Working on the same principles as how sweat cools the body, evaporative cooling solutions draw heat from workers' bodies, using an external source of water. They can provide an enhanced cooling effect, even for workers still acclimatizing to new tasks or to a change in environment. And they can help experienced workers keep their cool.

While any damp rag could provide some relief, controlled evaporation with fabrics that hold moisture for an extended period of time, and products that are comfortable to wear, will provide significantly more effective results for more productive workers.

Phase Change Cooling
Unlike evaporative cooling technology, airflow is not required for phase change cooling, making it a prime choice for high-heat indoor settings such as foundries, glass manufacturing, and paper & pulp operations. Solutions such as Phase Change Cooling Vests use a cooling charge pack that works to pull heat away from the body (heat energy always moves from a warmer place to a cooler place). These packs contain liquids, such as non-toxic phase change material, that solidify, typically between 55° F (13° C) and 64° F (18° C), but unlike conventional ice or gel freezer packs, phase change packs aren't frosty to the touch, so they'll remain comfortable against the body and stay cool a lot longer than ice. As the phase change cooling pack absorbs heat, it begins to change from a solid to a liquid. The cooling effect can last anywhere from an hour and a half to four hours, depending on the solution.

Absorptive Cooling
Sweat happens, and for a very good reason: to regulate body temp. But you know what they say about too much of a good thing. That's where absorptive technology comes in. A sweaty palm or stinging droplet in the eye isn't just uncomfortable, it's a job site hazard.

Much like evaporative cooling solutions, materials matter when it comes to all-around comfort and performance with absorptive solutions. Again, you could wrap any old rag around your head and call it good, but ultimately what starts as a solution becomes a hindrance because it just wasn't designed for that purpose.

From old-school but super-effective cotton terry sweatbands (think early '80s John McEnroe) to dew rags, skull caps, multi- bands, and headbands made of high-performance materials that pull sweat away from the body for fast evaporation, absorptive solutions help take the sting out of working in the heat.

Hydration
Heat-related illnesses such as heat rash, heat cramps, heat exhaustion, and heat stroke are closely associated with a worker's hydration level. Because heat stress is a widely recognized hazard, states including California and Washington have established specific workplace drinking water requirements as a major part of heat stress workplace controls. OSHA standards for both general industry and construction activities, as well as various safety guidelines, mandate that adequate drinking water is available to workers at all workplaces and job sites.

Dehydration risks are more commonly recognized for work performed outdoors in warm temperatures or for work in hot indoor environments such as foundries, bakeries, boiler rooms, kilns, etc. But they also exist for those toiling away in indoor job sites with poor airflow or workers who wear special protective clothing—such as non-permeable hazmat suits—as they face additional challenges.

Keeping clean, cool, and convenient water accessible to workers can prove to be more challenging than one would think. The use of hydration packs is a good way to not only solve for that challenge, but also encourage more intake of water. Because hydration packs make water so readily available and hands-free simple, workers can hydrate without having to take a break from the task at hand.

Shade
When work must be done in the heat of the day, taking regular breaks and meals under the cover of shelters such as canopies, umbrellas, and other temporary structures is important—so important, in fact, that states including Washington and California have regulations that require it.

Providing effective job site shade may require planning. Shelters should block direct sunlight with a purpose to provide a recovery area with access to fluids. Consider using areas with the natural shade of heavy tree cover or an awning or other temporary structure at the site. Take advantage of extra items such as a misting system, which can cool your shelter up to 30 degrees Fahrenheit below ambient air. If the structures are air-conditioned, even better!

This article originally appeared in the March 2019 issue of Occupational Health & Safety.